1. Field of Invention
The invention relates to an image forming apparatus for forming an image on a recording medium based upon image data, and more particularly relates to an image forming apparatus which is provided with a storage device for storing image data provided to form an image and which can form multiple images corresponding to image data stored in the storage device.
2. Description of Related Art
Heretofore, an image forming apparatus is provided with an image forming device for forming an image on a recorded medium based upon image data, a storage device for storing image data, a receiving device for receiving the image data stored in the storage device, and a controller for storing all of the image data received by the receiving device in the storage device if multiple images corresponding to the image data are required to be formed and for controlling the process so that the image forming device is driven multiple times based upon the stored image data.
In this type of image forming apparatus, image formation is enabled by storing all of the image data received via the receiving device, such as an interface, in the storage device, such as a memory, and controlled so that the image forming device such as a printer engine, is driven based upon the stored image data, multiple times. That is, as all of the image data is stored in the storage device, a copy of the images from the first page to the final page is formed and then, the number of desired copies of the images are formed by repeating the similar operation, multiple times. In this case, so-called collated printing (also called sort printing) wherein images from a first page to a final page are sequentially formed and stacked.
Also, in this case, as all of the image data is stored in the storage device, image data is not required to be sent from a computer, and the like, multiple times. Therefore, if the image forming apparatus is used in a printing system in which multiple computers and one printer (one image forming apparatus) are connected via a local area network (LAN), and the like, a series of image data from the first page to the final page only needs to be sent from a computer once.
However, in this type of image forming apparatus, when the storage capacity of the storage device is full while all of the image data is stored in the storage device, subsequent processing is disabled. In this case, the image forming apparatus may be halted with an error message displayed. If such a situation occurs, image data is required to be divided into small parts and sent again from a computer and the like, and collated printing in a smaller unit is required to be executed. In this case, sending image data by a computer, and the like, is troublesome.
An image forming apparatus that performs so-called stack printing in which desired copies of images are sequentially formed (i.e., multiple copies of a first page are printed, then a second page, etc.) can switch its operational mode from collated printing to stack printing at the beginning of a print job. However, in this case, image data is required to be re-sent. Further, in this case, before the image data is sent again, the setting of the image forming apparatus and data sent together with the image data for specifying a printing method and the like, are required to be changed. Therefore, in this case, a user is also required to perform a complicated task. Further, if the above situation occurs and the image forming apparatus is halted, image data cannot be sent from another computer, and the like. In this case, the entire system process is inconveniently halted.